Presser foot lock for shoe sewing machines



May 16, 1944. c. w; BAKER PRESSER FOOT LOCK FOR SHOE SEWING MAGiIINES Filed Nov. 14, 1941 Patented May 16, 1944 PRESSER FOOT LOOK FOR SHOE SEWING MACHINES Corwin WfBaker, Stoneham, Mass, assignor to United Shoe Machinery Corporation, Flemington, N. J., a corporation of New Jersey Application November 14, 1941, Serial No. 419,099

9 Claims.

The present invention relatesv to shoe sewin machines and more particularly to improvements in presser foot actuating mechanisms for wax thread machines of the type designed for connecting the welted upper and outsole of a Goodyear welt shoe with a lockstitch seam, as disclosed in U. S. Letters Patent to Ashworth No. 1,169,909, dated February 1, 1916, and to Ashworth and Whitaker No. 2,271,611, dated February 3, 1942.

In sewing together the welted upper and outsole of a Goodyear welt shoe, the resistance of the work materials operated upon to penetration and Operation of the stitch forming devices necessitates a relatively heavy clamping pressure to secure the work in place. The clamping ressure is relieved during each sewing cycle to enable the work to be fed a stitch length and is again applied first yieldingly with a light pressure and then with av renewed heavy pressure during the succeeding stitch forming cycle. Machines of the type above referred to are heavily constructed and when operated at high speeds, according to present day sewing practices, are frequently subject to extreme wear from vibration and similar causes.

In the machine of the patents referred to, a mechanical presser foot actuating mechanism having a frictional lock is employed to hold the clamping pressure on the work during; stitch formation. This lock is extremely efficient if properly adjusted but under certain circumstances, after excessive wear and accumulation of foreign matter along its frictional surfaces, it becomes noisy and ineffective for the purposes intended, particularly when operated at high speeds, thus rendering the entire presser foot mechanism incapable of securing the work in proper relation to the stitch forming devices. As a result, the spacing between stitches inserted by the machine becomes variable and difficulty is encountered by the operator in guiding the work to form an acceptable seam.

- The object of the present invention is to provide a presser foot actuating mechanism for a .shoe sewing machine of the type referred to which is not subject to the limitations affecting the usual mechanism having a mechanical presser foot lock and which may be operated to cause the work to be clamped and released in exact timed relation to the Work feeding movements of the stitch forming devices without undesirable effects from vibration, even though the connections in the mechanism become loosened or worn substantially.

In accordance with this object, the present invention relates to the provision in a shoe sewing machine having a yieldingly actuated presser foot and a work support for clamping and releasing the work, of presser foot actuating mechanism comprising a hydraulic lock controlled by a valve in place of the usual mechanical lock, such as disclosed in the patents above referred to. The use of a hydraulic lock in place of a mechanicalv lock is particularly advantageous where undesired vibrations are to be absorbed, due to the inherent vibration reducing character of fluids in general. In the present embodiment of this feature of the invention, the valve for controlling the lock is so arranged that as the valve is closed, a gradual reduction in flow of fluid therethrough or a throttling effect results, thus preventing impact which is conducive to vibration in the Dresser foot mechanism, as well asabsorbing the momentum of the actuating parts slowly.

In the illustrated form of this feature of the invention, the presser foot actuating mechanism comprises a floating lever connected with the presser foot and the actuating devices including the lock are connected to different points on the lever, the lever operating about a fulcrum which changes gradually as the lock becomes efiective from one of the points of connection to another.

With the use of a mechanical lock employing friction or ratchet teeth to prevent movement of the presser foot, the ordinary construction of lock is such that there is no intermediate stage of operation in which the parts are retarded in their movements before being gripped or stopped. A mechanical lock designed for use with a presser foot mechanism ordinarily is actuated either to lock or unlock the mechanism and the transition between locked and unlocked condition occurs practically instantaneously. With the present illustrated hydraulic look, there is a brief period of retardation as the lock is actuated which is useful to absorb and prevent vibrations caused by impact in th presser foot mechanism.

Other features of the invention consist in the devices, combinations and arrangements of parts hereinafter described and claimed which, together with the advantages to be obtained thereby, will be readily understood by those skilled in the art from the following description taken in connection with the accompanying drawing, in which Fig. 1 is a view in side elevation of certain portions of an outsole shoe sewing machine embodying the features of the present invention; and Fig. 2 is a detail view on a somewhat enlarged scale of the hydraulic presser foot lock shown in Fig. 1.

The machine illustrated in the drawing is of the type disclosed in the patents above identified and is equipped with a curved hook needle 2, a. curved work feeding awl 4, a shuttle or loop taker 6, a work support 8 and a presser foot It], all similar and operating in the same man-' ner, except as hereinafter pointed out, to those of the patents. The stitch forming devices and presser foot are actuated by a sewing shaft [2 driven through driving and stopping mechanisms similar to those disclosed in Patent No. 1,233,539 of July 17, 1917. The work is fed by the awl while in engagement with the work, the work being released from the clamping grip of the presser foot and work support during feed.

In the machine of the patents referred to, while the work is clamped, the presser foot is locked in position mechanically. For actuating the presser foot to clamp and release the work, mechanism is provided corresponding to a lever l4 engaging a cam l6 on the sewing shaft I2. The cam lever I4 is one of three actuating devices connected to a floating lever I8. Other devices include a spring 26 stretched between the frame of the machine and a pin 22 on a link 24. The link 24 is connected at a point defined by a pivot pin 26 on the lower end of the floating lever l8, the upper end of the floating lever being pivotally connected by a pin 28 through a link 30 to the cam lever. Between the upper and lower ends of the floating lever are a pair of pivot pins 32 and 34 for the mechanical presser foot lock and for a link 36, respectively. The link 36 is connectedto a presser foot supporting lever 38 fulcrumed on a shaft 39. The operation of the lock is such that as the cam lever I4 is moved by rotation of the cam 16, a relatively heavy clamping pressure of the presser foot is applied against the work on the work support, the floating lever fulcruming about the pivot pin 32 of the presser foot lock. When moved in the other direction, the cam lever l4 causes the presser foot to be raised from the work and held in raised position until the feed of the work is completed. After the work has been fed, the lock is released and the floating lever i8 swings about the pivot pin 28 as a fulcrum while the spring 20 acts through link 24, pivots 26 and 34, link 36 and lever 38 to bring the presser foot against the work with a relatively light yielding pressure. After bringing the presser foot against the work, the lock is actuated to prevent movement of the pivot pin 32 and the cam lever is moved to add to the pressure of the presser foot on the work imparted by the spring 20. The fulcrum of the floating lever is thus constantly shifting from the lock pivot pin 32 to the cam lever pivot pin 28.

The presser foot locks of any machine of this type must be constructed to act positively in preventing movement. Whenever frictional effects are depended upon to look a presser foot mechanism, these effects must be sufficiently accentuated by a suitable construction to arrest all movement instantaneously or else a chattering series of impacts will be produced. With a pawl and ratchet arrangement, impact between the teeth of the ratchet and the pawl is unavoidable. With any form of mechanical lock, therefore, Whether dependent upon the application of friction or upon the use of pawls and ratchets, the lock is actuated either to prevent movement or to release parts connected thereto without any ability to absorb energy effectively, no intermediate partially released condition occurring. With such forms of lock, the fulcrum of the floating lever I8 is changed practically instantaneously between two points, with the result that looseness in the parts due to wear or otherwise may cause damage and improper operation of the presser foot.

In the machine of the present invention, vibratory effects and possible breakage of parts in the presser foot mechanism are avoided by the use of a hydraulic lock in place of the usual mechanical one. The lock is so constructed that the vibration absorbing character of the fluid employed therein is retained in as large degree as practicable. In operation, the hydraulic lock which is connected by the pivot pin 32 to the floating lever I8 enables the presser foot to be actuated with a fine degree of accuracy and enables the fulcrum of the floating lever to change gradually between the pivot pin 28 and the pin 32 and at the same time tosecure the pivot pin 32 in fixed position with the same degree of rigidity as with the use of a mechanical lock. During high speed operation of the machine, at the time of locking and unlocking the lock, the lever It may be in a condition of relatively rapid motion and by the use of a hydraulic lock, this motion is absorbed in the shortest possible time and any vibratory effects from rebound or sudden impact as with the use of a pawl and ratchet are avoided.

In the illustrated machine, the hydraulic lock includes a pressure member connected through pin 46 by means of which the sliding link 39 is joined thereto, a slot 48 being provided in the uppermost side wall of the pipe 50 to receive the arm projecting from the piston. I

To control the movements of the piston 42,th ends of the pipe 50 are connected to a rotary valve housing 52 having a valve body 54. The

"valve body 54 is provided with a port 56 capable of admitting flow of oil sufl'icient for the most rapid movements imparted to the piston. The valve body 54 projects outside the housing 52 and at its outer end carries a spur gear 58 meshing with a gear segment at the lower end of an arm on a lever 60. The lever 60 is rotatably mounted on a rod 62 at the rear of the machine frame and has an arm which is acted upon by a springpressed rod 64 tending to rotate the valve body into a position where the flow of oil is blocked. To stop the lever 60 when the closed position of the valve is reached, the lever engages a lug'65 on the machine frame. To move the lever 66in the opposite direction and rotate the valve body into a position to admit flow of oil, the arm of the lever 60 connected to the spring-pressed rod 64 is arranged beneath a set screw 66 in a projection of a cam lever 68 actuated by a suitably shaped cam on the sewing shaft l2. The portion of the pipe 50 constitutes a cylinder surrounding the piston 42 and the remainder of'the confined space within the pipe is fllled with oil so that when the valve body 54 is fully closed, as shown in Fig. 2, the flow of oil in the pipe is blocked and the piston 42 is positively locked by the oil against movement in either-direction.

the port' 56- into and" out of alignment with the faces ofth'e-valve housing; a relatively gradual increase or' retardation of oil flow 1 is permitted. If 'anyof the parts connected'to thelock are in rapid-motion, vibratory "eifects produced by lock-'- ing or unlock-ing will be substantially absorbed by the throttling effects of the valve; Thusthere will be an'intermediate stage in the operation of the'lockbetween fully open or unlocked position and fully-locked or-"closed positionof the valve 52, 54,;in"whichvibratory'efiects or possibilityof breakage in theparts is greatlyreduced. The set'screw" 66 may' be-adjusted to-regulate-the amount'of opening-of" the valve. Dueto the reduction of vibratory efiects, a much greater accuracyin movement of the presser foot to clamp and release the work results, even though the pivots and connections with the floating lever are substantially worn and subject to a degree of lost motion far greater than would enable effective operation with a mechanical form of lock.

Besides enabling the presser foot mechanism to be actuated at high speeds without destructive vibration or impact, the use of a hydraulic lock is advantageous in that it is unnecessary to make any mechanical actuating connection to the pressure member of the lock, the lock control valve being located at a convenient distance from the pressure member. The pipe connection between the confined spaces at the ends of the pressure member is readily shaped to conform with the spaces available at one of the most crowded points in a shoe sewing machine of this type. With the control valve located at a distance from the pressure member, the actuating mechanisms for the stitch forming devices become less crowded and a better arrangement and design of these mechanisms is rendered possible. In certain of its aspects, the present invention is similar in nature to that disclosed in United States Letters Patent No. 2,321,596, granted June 15, 1943, for Presser foot mechanisms for shoe sewing machines, upon an application of Otto R. Haas, filed of even date herewith.

The nature and scope of the invention having been indicated and a particular embodiment thereof having been described, what is claimed is:

1. A shoe sewing machine having, in combination, stitch forming devices, a presser foot, a work support, and mechanism for clamping the work comprising a yielding member acting after the work is released to bring the presser foot against the work, a hydraulic pressure member connected to the presser foot, and a valve for preventing flow of fluid caused by pressure on said hydraulic member to hold the presser foot and work support from separation after the work is clamped.

2. A shoe sewing machine having, in combination, stitch forming devices, a presser foot, a work support, and mechanism for actuating the presser foot relatively to the work support to clamp and release the work comprising a yielding member acting after the work is released to bring the presser foot against the work, a hydraulic pressure member connected to the presser foot, and a valve connected with a fluid confining space at one end of the pressure member and constructed to produce a gradual flow retarding action on the fluid in the space before fully closing.

3. A shoe sewing machine having, in combination,. stitch" forming; devices; a; pressert'footia-z work support; and mechanism -forfactuatingithe? presser foot relatively to tliework" supportt to clamp and release the Work comprising ra y-ield;

ing member acting after the work' -is released" to bring the presser foot" against the work; a hydraulic pressure member'connected toth'epresser foot, a --f1uid 'passage having portions blocked by opposite ends ofthe pressureimemberand form inga cylinder for the pressure membentd-adin-it': flow of fluid in th'epassage'whemtl'ie pressure member ismoved, and avalve disposedin'ethe passage to prevent fluid flow;

4. A'shoe sewing-'macliine having; in combine"- tion, stitch forming devices, a presser footgaa work support, mechanisms for' actuating the presser foottowards and from" the work'= support to clamp and release the work during each sewing:- cycle comprising a floating lever, a' cam lever connectedat one" point to th'e' 'fioating lever; a yielding member connected at a second point to the lever, a double ended piston connected at a third point to the lever, a cylinder passage for the piston to admit flow of fluid when the piston is moved, and a valve in the passage for retarding movement of the piston in either of two directions to cause the floating lever to change its fulcrum gradually between the points of connections with the piston and with the cam lever as the valve is actuated.

5. A shoe sewing machine having, in combination, stitch forming devices, a presser foot, a work support, and mechanism for actuating the presser foot relatively to the work support to clamp and release the work comprising a yielding member acting after the work is released to bring the presser foot against the Work, a hydraulic pressure member connected mechanically to the presser foot for locking the presser foot against the work, a valve housing, a pipe forming a cylinder and being connected at opposite ends of the pressure member with the valve housing, a valve in the housing, and means for actuating the valve gradually to produce a flow retarding action on the fluid passing through the valve while being moved from fully opened to fully closed positions.

6. A shoe sewing machine having, in combination, stitch forming devices, a presser foot, 2. work support and mechanism for actuating the presser foot relatively to the work support to clamp and release the work comprising a yielding member acting after the work is released to bring the presser foot against the work, a hydraulic pressure member mechanically connected to the presser foot, a cylinder surrounding the pressure member, a rotary valve connecting fluid confining spaces at opposite ends of the pressure member in the cylinder, a gear on the valve, and a lever having a gear segment meshing with the gear on the valve for rotating the valve in opposite directions during each sewing cycle.

7. A shoe sewing machine having, in combina tion, stitch forming devices, a presser foot, a work support and mechanism for actuating the presser foot relatively to the work support to clamp and release the work comprising a yielding member acting after the work is released to bring the presser foot against the work, a hydraulic pressure member mechanically connected to the presser foot, a cylinder surrounding the pressure member, a rotary valve connecting fluid confining spaces at opposite ends of the pressure member in the cylinder, a gear on the valve, a lever having a gear segment meshing with the gear on the valve for rotating the valve in opposite directions during each sewing cycle, and means for regulating the amount of opening in the valve,

8. A, shoe sewing machine having, in combination, stitch forming devices, a presser foot, a work support and mechanism for actuating the presser foot relatively to the work support to clamp and release the work comprising a yielding member acting after the work is released to bring the presser foot against the work, a hydraulic pressure member mechanically connected to the presser foot, a cylinder surrounding the pressure member, a rotary valve connecting fluid confining spaces at opposite ends of the pressure member in the cylinder, a gear on the valve, a lever having a gear segment meshing with the gear on the valve for rotating the valve in opposite directions during each sewing cycle, a spring for moving the lever in one direction, a lug for stopping movement of the lever by the spring, a cam lever for moving the lever having the gear segment in the other direction against the force of the spring, and an adjusting screw for regulating the movement of the spring actuated lever.

9. A machine for manufacturing shoes having, in combination, devices for operating upon a shoe, members brought into contact with a shoe for clamping and actuated away from the shoe for releasing the shoe during each operating cycle of the machine, hydraulic pressure means connected to one of the clamping members, a valve for controlling the pressure on the hydraulic means, and mechanism for actuating the valve after the work is clamped to hold the clamping members in the same positions relatively to each other during action of the operating devices.

CORWIN W. BAKER. 

